worker: release native Worker object earlier

Destroy the `Worker` class earlier, because we don’t need access
to it once the thread has stopped and all resources have been
cleaned up.

PR-URL: #26542
Fixes: #26535
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: addaleax

src/node_worker.cc

@@ -136,6 +136,9 @@ Worker::Worker(Environment* env,
       env->inspector_agent()->GetParentHandle(thread_id_, url);
 #endif
 
+  // Mark this Worker object as weak until we actually start the thread.
+  MakeWeak();
+
   Debug(this, "Preparation for worker %llu finished", thread_id_);
 }
 
@@ -412,14 +415,10 @@ void Worker::OnThreadStopped() {
 
 Worker::~Worker() {
   Mutex::ScopedLock lock(mutex_);
-  JoinThread();
 
   CHECK(thread_stopper_.IsStopped());
   CHECK(thread_joined_);
 
-  // This has most likely already happened within the worker thread -- this
-  // is just in case Worker creation failed early.
-
   Debug(this, "Worker %llu destroyed", thread_id_);
 }
 
@@ -508,6 +507,10 @@ void Worker::StartThread(const FunctionCallbackInfo<Value>& args) {
   ASSIGN_OR_RETURN_UNWRAP(&w, args.This());
   Mutex::ScopedLock lock(w->mutex_);
 
+  // The object now owns the created thread and should not be garbage collected
+  // until that finishes.
+  w->ClearWeak();
+
   w->env()->add_sub_worker_context(w);
   w->thread_joined_ = false;
   w->thread_stopper_.SetStopped(false);
@@ -517,6 +520,7 @@ void Worker::StartThread(const FunctionCallbackInfo<Value>& args) {
     CHECK(w_->thread_stopper_.IsStopped());
     w_->parent_port_ = nullptr;
     w_->JoinThread();
+    delete w_;
   });
 
   uv_thread_options_t thread_options;
@@ -544,6 +548,7 @@ void Worker::StopThread(const FunctionCallbackInfo<Value>& args) {
   Debug(w, "Worker %llu is getting stopped by parent", w->thread_id_);
   w->Exit(1);
   w->JoinThread();
+  delete w;
 }
 
 void Worker::Ref(const FunctionCallbackInfo<Value>& args) {